The word itself often evokes a chuckle, but a fartlek session is anything but a joke of a workout.

Fartlek is a Swedish word that means “speed play,” but practically it means you’re playing with speed by alternating between faster and slower bouts of running during a workout. The length and speed of the faster “pickups,” as well as the slower recovery intervals, will vary depending on your training focus, but the alternating between faster and slower runs in a non-stop run will be similar.

Fartlek training is a safe and effective way to jump-start and fine-tune your training after you’ve put in a few weeks of base training. Plus, alternating speeds during a workout can be a lot of fun compared to running the same pace for something like a typical 45-minute run.

“The most important aspect of a fartlek is that you never stop running,” says Kevin McCarey, a San Diego-based running coach. “This makes the fartlek a continuous run and more like a race itself, as opposed to an interval workout where you stop and rest, which you would never do in a race.”

McCarey has emphasized the fartlek during structured, intense phases of training while coaching a number of high-profile endurance athletes, including Canadian runner/triathlete Carol Montgomery, Olympic triathlon silver medalist Michellie Jones, U.S. 50K record holder Josh Cox, and a large group of U.S. Olympic Trials qualifiers, including 2003 marathon world championship competitor Tamara Lave, who ran a 2:37 PR while working full-time as a lawyer.

While a fartlek can be done on any terrain, McCarey prefers a big grass field, as it allows slower athletes to cut corners and effectively compete with the faster athletes, pushing them to new heights in the process.

“I encourage everyone to cheat, cheat, cheat,” McCarey says. “That’s one of the best parts about doing fartleks on a big grass field.”

McCarey also requires his athletes to regroup after every interval, with the faster athletes jogging back towards the slower athletes during the rest period.

“This allows so many people at different abilities to run together and improve in a way that they never could if they were running by themselves, or even with a group of runners who are more their speed,” says McCarey, who also likes that all his athletes, no matter their ability, get their heart rates elevated for the same duration of time.

Fartleks can also be implemented early on in a training phase, when an athlete is returning from a break or coming back from injury.

“If someone is coming back from an injury or time off, they’re not going to be in great shape, and it can hurt someone’s confidence if they go to a track and do a workout at slower times than they would normally run,” says Michael McKeeman, a coach at Run Mammoth Performance Coaching and a longtime training partner to American marathon record holder Deena Kastor.

To counter this ego blow, McKeeman will often have his athletes run fartleks over rolling hills or on a large grass field.

“I’ll use the environment to help map out what the fartlek will be,” says McKeeman. “I might tell them to run hard on the uphills and take it easy on the downhills. Or, if I know an athlete likes to run around a large athletic field, I might tell them to run hard on one side of the field and take it easy on the other.”

McCarey also makes use of the environment during certain fartlek workouts. For example, if it’s ever raining or windy during a fartlek workout, McCarey will have his athletes run 90-second intervals with the wind, effectively giving their bodies a speed boost and teaching them how to efficiently run at a pace they couldn’t maintain without the aid of the wind. His athletes will then jog back to the place they started the first 90-second interval, so that they can use the wind each time.

Like McCarey, McKeeman also uses fartlek workouts during more structured phases of training, with his athletes usually completing one session a week. Both coaches believe pace control during fartlek workouts is key, and beginners often run their fartleks too hard.

“Most beginners do the speed phase of the fartlek too fast, which can force them to walk during the workout,” McCarey says. “But this is actually the opposite idea behind a fartlek. You should never, ever walk.”

Nevertheless, if a runner makes a pacing mistake and is reduced to a walk, McKeeman says to just chalk it up to a learning experience.

“People tend to think they’re not running hard enough when they’re not seeing splits,” McKeeman says. “They run too hard and then they’re trashed at the end of the fartlek, but the important part is they learn from this, so that when they’re in a race they’ll have a better feeling for how hard they should be going.”

McCarey says that athletes who lack a strong running background shouldn’t do more than 5 x 2-minutes hard with 90 seconds of easy jogging in between when first starting out. National class age-group runners, on the other hand, will do upwards of 3 x 10 minutes with 5 minutes of easy jogging in between. The pace should be one they can maintain throughout the workout, but the effort will get significantly harder as the workout progresses.

As a general rule, McCarey says that intervals of 2 to 4 minutes should be countered with 90 seconds of easy jogging, intervals of 5 minutes should be countered with 2 minutes of easy jogging, and intervals of 10 minutes should be countered with 5 minutes of easy jogging. McCarey likes to end every fartlek workout with four to six 40-second strides over a small hill, with 1:20 of easy jogging in between.

These strides — short pickups performed slightly faster than 5K race pace — teach runners to hold their form at the end of the race, and the hill improves the athlete’s overall strength and helps create a mini-core workout.

Every four weeks or so, McCarey also throws a timed mile to the end of his fartlek session, where all his runners line up at the beginning of a pre-measured mile and run the full distance as fast as they can.

“This is where everyone wants to go all out,” McCarey says. “The mile is used as a measuring stick, so that athletes can see if they are improving.”

Practice fartleks in this way, and you’ll be seeing your next PR in no time.

Sample Fartlek Workouts

Do these workouts once every other week for 2-8 weeks before a given race.

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